Acoustic emission (AE) testing is an increasingly popular technique used for nondestructive
evaluation (NDE). It has been used to detect and locate defects such as fatigue cracks in
real structures. The monitoring of fatigue cracks in plate-like structures is critical for aerospace
industries. Much research has been conducted to characterize and provide quantitative
understanding of the source of emission on small specimens. It is difficult to extend these results to
real structures as most of the experiments are restricted by the geometric effects from the specimens.
The aim of this work is to provide a characterization of elastic waves emanating from fatigue
cracks in plate-like structures. Fatigue crack growth is initiated in large 6082 T6 aluminium alloy
plate specimens subjected to fatigue loading in the laboratory. A large specimen is utilized to
eliminate multiple reflections from edges. The signals were recorded using both resonant and nonresonant
transducers attached to the surface of the alloy specimens. The distances between the
damage feature and sensors are located far enough apart in order to obtain good separation of
guided-wave modes. Large numbers of AE signals are detected with active fatigue crack
propagation during the experiment.
Analysis of experimental results from multiple crack growth events are used to characterize the
elastic waves. Experimental results are compared with finite element predictions to examine the
mechanism of AE generation at the crack tip.
Fatigue Crack Growth Characterisation of RAFM Steel using Acoustic Emission Technique
